Hospital-based epidemiology: a strategy for 'dealing with Clostridium difficile'

Clostridium difficile-associated diarrhoea (CDAD) remains a major infection control problem. Uncertainty remains over methods of diagnosis and definitions for ascertaining provenance of cases. We undertook a prospective epidemiological study to better ascertain local epidemiology of 275 new cases (general practitioner and hospital) diagnosed in a large teaching hospital in the UK. The highest incidence of cases was found in haematology and critical care and a surprisingly high proportion, 29%, of hospital cases occurred in those aged <65 years. Fifty-five cases were diagnosed within 48h of admission. Of these, those defined as 'community-acquired' varied between 9 and 25 according to various proposed definitions relating to acquisition and onset of diarrhoea. Of 48 community-onset cases, this number varied between 19 and 25, the variability making comparisons between National Health Service (NHS) trusts potentially inaccurate. Cases were followed for 90 days after diagnosis and all cause mortality data obtained. Of 227 cases diagnosed in hospital, 56 (25%) died within 30 days, 29% of whom were aged <65 years. Death certification data were available in 86% of these cases. C. difficile was recorded on 15 (31%) certificates and as a primary cause (1a or 1b) in 8 (17%) cases. Our study shows the value of local epidemiology for planning infection prevention and control strategies within an NHS trust and for contributing to the evidence base for national targets and policies.